Transmission of an optical signal through optical fibers connected in series with each other suffers from optical loss and reflection caused by the gap between the terminal surfaces of the fibers. In a method widely used for connecting optical fibers with lowered optical loss, the terminal surface of the connector for connecting the optical fibers is formed to be spherically projected and polished to form a mirror surface so that the terminal surfaces of optical fibers are contacted closely with each other.
A conventional apparatus used for forming the end surface of an optical connector into a spherical mirror surface is composed of a grinding table having a circularly recessed guide surface, a grinding tape running across the recessed guide surface (in the tangential direction), means for pressing the end surface of the optical connector onto the recessed guide surface of the grinding table with the grinding tape interposed therebetween, means for drawing the grinding tape across the curvature of the recessed guide surface, means for rotating the optical connector around its axis, and means for moving the optical connector in the direction orthogonal to the running direction of the grinding tape while the optical connector is rotated.
For forming the end surface of an optical connector into a spherical mirror surface using the conventional apparatus, the end surface of the optical connector is pressed onto the recessed guide surface of the grinding table with the grinding tape interposed therebetween, the grinding tape drawn by the drawing means is allowed to run across the curvature of recessed guide surface and, at the same time, the optical connector is rotated around its axis and moved back and forth in the direction orthogonal to the running direction of the grinding tape, by the rotating means and the moving means, respectively, thereby the end surface of the optical connector pressed on the curved surface of the grinding table is finished to form a mirror spherical surface by the help of the grinding tape.
For connecting optical fibers by means of an optical connector, an optical fiber is inserted into a ferrule and fixed to the ferrule with some adhesive.
When the end surface of an optical connector is formed into a spherical mirror surface by the use of the conventional apparatus mentioned above, however, there often arises a problem in which the end of optical fiber is receded from the end surface of the optical connector, because the optical fiber is ground more readily than the ferrule around the optical fiber. This recession may cause failure in close contact of the optical fibers with each other at their ends.